Topping vs. LST: Which Training Method Wins on Yield?

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Somewhere around week three of veg, every grower stares at their plant and asks the same question: do I cut the top off this thing, or just bend it into submission? It's not a trivial question, and it's one that comes up whether you're running a single autoflower in a closet or forty photoperiods in a 4x8 tent. Topping and low-stress training (LST) are the two most common answers, and they both attack the same biological target -- apical dominance, the plant's built-in tendency to funnel resources into one dominant central stem instead of spreading growth laterally.

They just get there through completely different mechanisms. One involves a blade and an open wound. The other involves string, ties, and patience. Neither is a gimmick -- both have decades of grower experience and a reasonable amount of horticultural science behind them. But the choice you make here isn't academic. It changes your harvest date, how many hours you'll spend hunched over a canopy with garden ties, and whether you end up with one thick central cola or a wide, even field of colas all fighting for the same light. The real question isn't which method is objectively better -- it's which one fits the strain you're running, the timeline you're working with, and the physical constraints of your grow space.

How Topping Actually Works

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Topping falls into the category growers call high-stress training, or HST, and the name is accurate -- you're taking scissors or a blade to the main stem's growth tip and removing the apical meristem entirely. That's the cluster of actively dividing cells at the very top of the plant responsible for upward growth. It sounds brutal, and in a sense it is, but it's also one of the oldest tricks in cultivation because of what happens next at the hormonal level.

The apical meristem is the plant's primary source of auxin, the hormone responsible for suppressing lateral bud development everywhere below it. This is apical dominance in action -- the plant prioritizes vertical growth from a single point and keeps its lower branches dormant or subordinate. Cut that tip off, and auxin production at that location stops cold. Within days, the auxin gradient that was suppressing the two nodes just below the cut collapses, and those previously dormant lateral branches wake up and start competing for the role the main stem used to play.

The visible result is a bushier, wider plant with multiple colas instead of one dominant spire. Instead of a single main stem racing for height, you get two, four, sometimes more co-dominant growth points, each developing its own cola through flowering. This is the entire appeal of topping -- it trades height for lateral expansion and bud site count.

That transformation isn't instant, though. Expect a recovery window of roughly 10 to 14 days where the plant looks like it's stalled. It hasn't -- it's rerouting energy away from stacking height and into healing the wound and pushing new lateral growth. Cutting during this window, or stressing the plant further with nutrient changes or transplanting, just extends the delay.

Timing the cut matters more than most first-time growers realize. The sweet spot is early-to-mid vegetative growth, once the plant has developed 4 to 6 nodes. Topping too early, before the plant has enough established root mass and node structure, risks stunting it. Topping too late, closer to the flip to flower, doesn't leave enough runway for the plant to recover and develop those new colas before it needs to shift into flowering mode.

How LST Actually Works

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LST takes the opposite philosophical approach. Instead of removing tissue, you're gently bending branches away from vertical and securing them in that position -- soft plant ties, twine, or plant yo-yos anchored to the pot rim or a frame. Nothing gets cut, nothing gets wounded. The plant's physiology stays fully intact from the moment you start.

Because there's no cutting involved, the mechanism behind LST has nothing to do with auxin disruption. It's purely about geometry and light. A plant left to grow naturally puts most of its energy into one tall central cola while lower branches sit in the shade of the canopy above them, getting a fraction of the light intensity and producing airy, underdeveloped popcorn buds. Bending the main stem and upper branches outward and downward flattens that vertical hierarchy into something closer to a level canopy, pulling previously shaded lower bud sites up into direct light and evening out how photons get distributed across the whole plant.

Most growers start LST early in veg, as soon as branches have enough length and flexibility to bend without snapping, and they keep adjusting throughout the grow -- retying, redirecting new growth, tucking taller branches back down as the plant fills in. Training typically continues right up until the first week or two of flowering, at which point the branch structure is locked in and you let the plant do its thing.

The absence of an open wound means there's no real recovery downtime built into the technique. The plant keeps photosynthesizing and adding new growth throughout the process, even on the day you're actively bending and tying it. That's a meaningful practical advantage for growers on a tight schedule, since you're not losing one to two weeks to recovery the way you are with topping.

LST tends to shine hardest in indoor setups with fixed-height lighting -- a single LED panel or bar mounted at a set distance from the canopy, where evenness matters more than raw single-cola size. If your light can't move up as the plant grows, keeping the canopy flat and uniform is often more valuable than letting one branch dominate.

Yield Numbers: What the Data Actually Shows

The yield numbers around topping get thrown around a lot, and the commonly cited figure -- up to 30% more yield compared to an untopped plant -- holds up reasonably well in practice, particularly in outdoor grows where the season is long enough to absorb the extra time topping requires. Outdoor plants with months of vegetative runway and unlimited vertical space are the ideal candidates: you get the full benefit of multiple colas without the tradeoffs biting as hard.

Those tradeoffs are real, though. Topped plants generally take an extra 1 to 2 weeks to finish flowering compared to an untopped plant of the same strain, because the plant needs that recovery window before it's even back to full vigor, on top of however long it needs to fill out multiple cola sites. And the central cola on a topped plant is usually smaller and less dense than what you'd get from an untopped main stem, since it's now sharing hormonal and nutrient priority with its new co-dominant siblings. That's offset -- often more than offset -- by stronger, more developed lateral colas that would otherwise have stayed small and underdeveloped.

There's a quality wrinkle worth noting too: topped plants often show richer myrcene content in finished flower. Myrcene is one of the more sedating, earthy-smelling terpenes common in cannabis, and its increased presence in topped plants is a secondary effect worth factoring in if terpene profile matters to your goals, not just yield.

LST doesn't produce anything close to that 30% jump in most cases. Its gains come from a different place entirely -- better light penetration to lower bud sites and a more even spread of developed buds across the canopy, rather than a dramatic increase in total flower mass. You're optimizing what the plant already has rather than forcing it to grow more growth points.

None of this happens in a vacuum. How aggressively a plant responds to topping is heavily strain-dependent -- some phenotypes throw vigorous, fast-recovering lateral branches after a cut, while others sulk for weeks and barely branch out at all. Outcomes always vary by climate, setup, and genetics, and starting with quality, well-bred seeds makes either method behave far more predictably than working with unstable or unknown genetics.

The Trade-Offs Nobody Puts on the Label

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The 30% yield bump on topping doesn't come free, and the cost is almost entirely time and attention. You're paying for it with the 10-to-14-day recovery window plus another 1 to 2 weeks of extended flowering, which adds up to nearly a month of extra grow cycle length compared to a plant you left alone. On a home grow with one crop running at a time, that's a real scheduling cost, not just a rounding error.

It's also genuinely labor-intensive to execute well. You need to time the cut correctly, monitor the recovery period closely for signs of stress or infection at the wound site, and typically follow up with selective defoliation later to keep the newly competing colas from shading each other out. This is a large part of why most large commercial cultivation facilities skip topping almost entirely -- it doesn't scale. When you're managing hundreds or thousands of plants, the extra hands-on labor per plant multiplies fast, and the extended cycle time eats into how many harvests you can turn per year.

Commercial operations with plenty of vertical headroom also tend to have different priorities than the home grower chasing max yield per plant. When your light can move up with plant height and floor space is the real constraint, maximizing individual bud size and consistency across a sea of plants usually matters more than multiplying bud count on any single plant. Topping's whole value proposition -- more colas per plant -- is less relevant when you can just run more plants instead.

LST's costs show up differently but they're not smaller. There's no single big time expenditure like a recovery window, but there's a steady drip of labor throughout the entire vegetative stage -- checking ties, retying branches as they thicken and outgrow their restraints, redirecting new growth that wants to shoot back upward. Skip a few days of maintenance and branches can snap back toward vertical or, worse, snap outright if they've gotten too rigid to bend safely.

LST also has a physical footprint cost that topping doesn't: bending branches outward means the plant needs more lateral room to spread into, which translates to a taller tent isn't the issue so much as needing wider spacing or a bigger footprint per plant. Neither method is something you set up once and forget about -- they just demand attention at different points in the timeline.

Why Most Experienced Growers Combine Both

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In practice, experienced growers rarely treat this as an either-or decision. Topping and LST get combined constantly, often alongside selective defoliation, because each technique solves a problem the other one leaves behind.

The common sequence looks like this: top the plant once, early in veg, to establish 2 to 4 main co-dominant colas. Once those branches have grown out a bit and regained vigor, start LST on each of them individually, spreading them outward and securing them so they develop under even light exposure instead of clustering together and shading each other. This combination captures topping's core advantage -- more total bud sites and higher yield ceiling per plant -- while using LST to fix the exact weakness topping creates on its own, which is an uneven, competing canopy where some colas end up shaded by others.

There's also an interesting timing variation worth knowing about that most home growers never hear of. A 2020 peer-reviewed study by Gaudreau, Missihoun, and Germain, published in Plant Science Today, looked at topping mother plants before taking clones rather than topping the clones themselves later in veg. Cuttings taken from already-topped mothers developed axillary shoots noticeably faster than cuttings taken from untopped mothers, cutting somewhere in the range of 7 to 10 days off the total cutting-to-harvest timeline.

The logic makes sense once you think it through: the hormonal disruption and lateral branching response has already happened at the mother plant level before the cutting is even taken. The resulting plantlet skips its own individual recovery period entirely, since it's essentially cloned from tissue that's already past that stress event. Compared to the standard approach of topping each plant individually during its own veg stage, this method shaved nearly two weeks off the timeline while matching standard topping's yield output.

The broader lesson here goes beyond just this one study. It's not only which technique you pick -- topping, LST, or both -- but when in the plant's lifecycle you apply the stress. Stressing a mother plant, a fresh clone, or an established vegging plant each produces a different practical outcome, even when the underlying mechanism is identical.

There isn't a universal winner here, and anyone who tells you there is hasn't run both methods side by side enough times. Topping trades time and labor for a genuinely higher per-plant yield ceiling -- more colas, more total flower, at the cost of a longer cycle and more hands-on management. LST trades away that dramatic cola-size jump for reliability, lower physiological risk, and a canopy that makes efficient use of whatever light you've got fixed above it.

The right call comes down to matching the method to your actual constraints rather than chasing whichever number sounds more impressive. Outdoor growers with a long season ahead of them and no ceiling to worry about are in the best position to take advantage of topping's extra yield and extended timeline -- the tradeoffs barely register when you've got months of sunlight to work with. Indoor growers working in a tight tent under a fixed-height light, where evening out the canopy matters more than swinging for one giant central cola, will usually get more consistent, less risky results out of LST.

Whichever route you take, the plant's genetics set the ceiling on how well it responds to either technique -- a vigorous phenotype will throw strong lateral colas after topping or bend cleanly into an LST frame, while a weak or unstable one will disappoint you no matter how well you execute the technique. That's ultimately the bigger lever. Starting with well-bred seeds from a source that breeds for structure and vigor matters more, in the long run, than obsessing over the exact timing of a topping cut or the perfect tie-down angle.